NASA scientists on the trail of mystery molecules

May 25, 2011

(PhysOrg.com) -- Space scientists working to solve one cosmic mystery at NASA's Ames Research Center, Moffett Field, Calif., now have the capability to better understand unidentified matter in deep space. Using a new facility so sensitive that it can recognize the molecular structure of particles in space, researchers now are able to track unidentified matter seen for the last century absorbing certain wavelengths of light from distant stars.

Astronomers suspect that one family of carbon-containing compounds, called polycyclic (PAHs), are the long-sought matter that produces holes in from multiple wavelengths. Researchers compared laboratory data of PAHs, measured in this unique facility that simulates space-like conditions, with an extensive set of high-resolution optical astronomical data. With this approach, they were able to survey the mysterious spectral signatures seen in both and emission that are common throughout and determine the abundance of PAHs.

"It is important to understand how PAHs absorb stellar radiation, and how they emit it back, because it contributes to the global energy balance in space," said Farid Salama, a space science researcher in the Astrophysics Branch at Ames. "Now, we can offer a clear and unambiguous explanation for the presence (or the absence) of specific PAH molecules in the interstellar medium." This research will be presented today at the American Astronomical Society meeting in Boston, Mass.

The research helps solve a problem scientists have struggled with for most of the century. They have detected more than 500 interstellar absorption lines in the spectra (range of frequencies or color) of starlight approaching Earth. Absorption lines are discrete colors of light absorbed by intervening matter; this absorption leaves holes or "lines" in the spectra. The lines are called diffuse interstellar band.

"PAHs are excellent candidates to account for the infrared emission bands seen in the interstellar medium," said Salama. "But their signature also must be seen in the visible and ultraviolet. This evidence was missing until now, because of the lack of relevant laboratory data."

PAHs are very stable and thought to be ubiquitous in the . They are flat molecules of carbon and hydrogen that form hexagons – their skeleton looks like chicken wire. On Earth, they can be found in coal, soot, and automobile exhaust.

By mimicking realistic interstellar conditions in the laboratory, Salama and his colleagues measured the spectra (fingerprints of molecules) of large PAHs and ions in the ultraviolet and visible light bands and compared the data to high-resolution astronomical data from the Ultraviolet and Visual Echelle Spectrograph instrument of the Very Large Telescope at the European Southern Observatory.

To achieve these results, Salama and his team used a unique specialized facility, called the Cosmic Simulation Chamber (COSmIC), which integrates a variety of state-of-the-art instruments to allow scientists to form, process and monitor simulated space conditions for interstellar materials in the laboratory. The chamber recreates the extreme conditions in space, where average temperatures can be as low as 100 Kelvin (less than -170 degree Celsius), densities are quadrillionths of Earth's average atmospheric density at sea level, and interstellar molecules and ions are bathed in stellar ultraviolet and visible radiation. Interstellar and ions must be stable enough to survive in this harsh environment.

Explore further: How the physics of champagne bubbles may help address the world's future energy needs

add to favorites email to friend print save as pdf

Related Stories

NASA Reveals Key to Unlock Mysterious Red Glow in Space

Aug 02, 2010

(PhysOrg.com) -- NASA scientists created a unique collection of polycyclic aromatic hydrocarbon (PAH) spectra to interpret mysterious emission from space. Because PAHs are a major product of combustion, remain ...

Cosmic Cockroaches

Sep 03, 2007

Starved. Stomped. Radiated. Poisoned. It's all in a day's work for the common household cockroach. The abuse these creatures can withstand is amazing.

Component of mothballs is present in deep-space clouds

Sep 02, 2009

(PhysOrg.com) -- Interstellar clouds, drifting through the unimaginable vastness of space, may be the stuff dreams are made of. But it turns out there's an unexpectedly strange component in those clouds, and it's not dreams ...

Recommended for you

What's next for the Large Hadron Collider?

Dec 17, 2014

The world's most powerful particle collider is waking up from a well-earned rest. After roughly two years of heavy maintenance, scientists have nearly doubled the power of the Large Hadron Collider (LHC) ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.